A projector which receives an image signal from a PC and projects a PC display image onto a screen and the like has become popular in recent years. The projector is used for projecting a presentation document created by a PC onto a screen, so that it is possible to present the content of information visually, and such a projector is widely used on the occasions of conference, study meeting and so on.
The PC and the projector usually transmit and receive an image signal from each other by an analog connection through an RGB cable. However it is bothersome that a user needs to connect the PC and the projector each time. Moreover, in the case where, for example, the data to be projected is stored in plural PCs separately, the PC and the projector requires to be reconnected. In view of this, a wireless image transmission apparatus has been suggested as an alternative method to transmit an image signal from a PC to a projector by an infrared or a wireless LAN for the purpose of improvement in using the projector, and also a wireless transmission system to concurrently show image signals transmitted from plural PCs to one projector is also disclosed (for example refer to Patent Reference 1).
Patent Reference 1: Japanese Laid-Open Patent Application No. 2003-330436.
However, according to the above-mentioned wireless transmission system, the display area to be assigned to each PC is actually determined at the projector side. Therefore, there exists a problem in which various types of presentations cannot be performed by this system.
Moreover, according to the above-mentioned wireless transmission system, an image signal of a PC is transmitted to the projector directly. Therefore, there exists a problem that traffic in the transmission path is expanded. Particularly, the transmission rate for the major standard of the current wireless LAN (IEEE802.11b) is approximately 11 Mbps, while the transmission rate for the standard which is expected to be developed in the future (for example IEEE802.11 g) is approximately 54 Mbps. Therefore, it is desirable to reduce the traffic in the transmission path between a PC and a projector to the utmost extent.
In view of the above-mentioned problems, an object of the present invention is to provide an image transmission system which enables to perform various types of presentations and also to reduce the traffic in the transmission path at the same time.